The reciprocal of 1 1 is, the inverse number is, the absolute value is 2, and the algebraic expression is: polynomial of the second term. 3. Calculation: (1)-4× (-3) ÷ (-2) = (2)-32-[(-2) 2+(1-) ÷ (-2)] = (3) = (4) 4. Simplify and evaluate:, where a=-2 and x=3. 5, simplify first and then evaluate:, where 6. Solve equations. ( 1) (2) (3); (4).7. If "!" Is a mathematical operation symbol, and 1! = 1,2! =2× 1=2,3! =3×2× 1=6,4! =4×3×2× 1, …, then the value of is () 8. If the equation (m- 1) x+2 = 0 is a linear equation about x, then the value of m is .9. If it is the solution of the equation, then it is =. 10. then x= 1 1, if x=2 is the solution of equation 2x+3k- 1=0, then the value of k is _ _ _ _ _ _ _.12, if the solution of equation 2x+k=x- 1 13; If x=2 is the solution of the equation mx+5x= 14, then m =14; If the value of the algebraic expression is equal to 2, then X is ()15; If sum is a similar term, then m-n= 2 1 For the review of the first calculation problem, it is known that x = -2 is the root of equation 2 (x-m)= 8x-4 m. With respect to x, m= 2, in the polynomial, it is arranged as the value of 3,4, assuming, and .5, if, and. The value of the algebraic expression is 1, then m= 7, then 8, which is the second term and the coefficient is; 9. Equation (k-2)x2+kx+ 1=0 is a linear equation about x (that is, x is unknown). Find the solution of this equation. What is the value of 10.X, and the sum of equations x-5 and 3x+ 1 is equal to 9? 1 1 is known, and. 12, 3-5y+2-6=0 is a linear system of equations about x, then x= n= solution. 13 and equation 5ax- 10=0 are 65438 about x. 16. Write a similar project _ _ _ _ _ _ _ _ _ _. 17, a two-digit number, where one digit is a, and the ten digit is 2 larger than the one digit, then the two digits are _ _ _ _. The algebraic expression is meaningless, x = _ _ _ .2, the coefficient of single term is, and the degree is. 3. Known; │ │=0, then 4. If they are opposite numbers and are not zero, the value is 5. (1) it is known that A = 3a2b-Ab2 and B = Ab2-3a2b. Find the value of 5a-b; (2) If ︱ a+︱+(b-) 2 = 0, find 5a-b6, and it is known that the solution of the equation is also the solution of the equation about X, and (1) find the values of m and n; 7.8. If known and still monomial, then 9. If and are known to be similar, the value of is10; If yes, it is 1 1,1+2+3+4+5+...+1000 = 65500.13 calculation (1) = (2 It is known that in △ABC, AQ=PQ, PR=PS and PR. ②QP∑AR； ③△BRP?△CSP, where (). (a) All correct (b) Only ① correct (c) Only ① correct (d) Only ① correct, ③ correct 2. As shown in Figure 2, point E is on the extension line of BC, so it cannot be judged that ABC is () A. ∠ 3 = ∠ 4B. ∠ B = ∠ DCE C. ∠1= ∠ 2.d. ∠ D under the following conditions. 4 As shown in the figure, the sides AB and AC of the straight line DE intersect △ABC at D and E, and intersect the extension line of BC at F. If ∠ B = 67, ∠ ACB = 74, ∠ AED = 48, find the degree of ∠BDF. 5. As shown in the figure: ∠ 1 = ∠ 2 = ∠ 3, complete the reasoning process and indicate the reasons: (4) Because ∠ 1 = ∠ 2, _ _ _ _ () Because ∠/kloc. With the following groups of line segments as sides, triangles can be formed by () A.2cm, 3cm, 5 cm B.5 cm, 6cm, 10 CMC.66. 3 cm d.3 cm, 4cm, 9cm7. One side of an isosceles triangle is equal to 4 and the other side is equal to 9. Then its circumference is () a. 17b.22c. 17 or 22d. 13 8. ∠A= ∠B= ∠C △ABC is () A. Acute triangle B. Right triangle C. Oblique angle. Its vertex angle is () A.30 B.75 C. 105 D.30 or 75 10. The sum of the inner angles of a polygon is 180, which is more than twice the sum of its outer angles. The number of sides of this polygon is () a.5b.6c.7d.8 The first triangle is 2 1, as shown in the figure, BC⊥CD, ∠ 1=∠2=∠3, ∠ 4 = 60, ∞. Why? (2) What is the degree of ∠ 5? (3) Find the internal angle degree of quadrilateral ABCD. 2.ABC, ∠ A = 50, ∠ B = 60, then ∠ A+∠ C = _ _ _ _ _ _ 3. It is known that the ratio of the degrees of the three internal angles of a triangle is 65436. Then this triangle is () A. Acute triangle B. Right triangle C. Oblique triangle D. Uncertainty 4. In △ ABC, ∠A=∠B+∠C, then ∠ A = _ _ _ _ degrees. 5. As shown in figure 1, ∠1+∠ 2+∠ 3+∠ 4 = _ _ _ _ degrees. 6. As shown in the figure, in △ABC, AD is the height on BC, and AE bisects ∠BAC, ∠ B = 75, ∞. Find ∠DAE and ∠AEC degrees. 7. The following statement is wrong: (a) The three heights of a triangle must intersect at a point inside the triangle. The three median lines of a triangle must intersect at a point inside the triangle. The three bisectors of a triangle must intersect at a point inside the triangle. Three heights of a triangle may intersect at an external point. 8. If the intersection of three heights of a triangle happens to be this point and the vertex of an angle, then the triangle is () A. Acute triangle B. Right triangle C. Oblique triangle D. Uncertainty 9. As shown in the figure, BD= BC, then the center line on the side of BC is _ _ _ _ _, and the area △ △ABD = _____ △ABC.

10. As shown in the figure, in △ABC, the heights of CD, BE and AF intersect at point O, then the three heights of △ BOC are line segments _ _ _ _ _ _ _. The first triangle is 3 1. In the figure below, () a, trapezoid b, diamond c, triangle d and square 2. As shown in the figure.

3. As shown in the figure, ∠BAD=∠CAD, AD⊥BC, vertical foot is point D, BD = CD. Do you know which line segments are the bisector, midline or height of which triangle?

4. As shown in Figure 5, in the isosceles triangle ABC, AB=AC, a median line BD on the waist divides the circumference of the isosceles triangle into two parts, 15 and 6, and then calculates the waist length and the bottom length of the isosceles triangle.

5. There is a triangular seed test base, as shown in the figure. Due to the introduction of four excellent varieties for comparative tests, this land needs to be divided into four pieces with equal areas. Please make more than two division schemes for you to choose (drawing description).

6. As shown in the figure, in △ABC, D and E are the midpoint of BC and AD respectively, and S△ABC=4cm2. Looking for S △ Abe. 7. As shown in the figure, in the acute angle △ABC, CD and BE are the heights of AB and AC respectively, and CD and BE intersect at point P, if ∠ A = 50.

8 As shown in Figure 7- 1-2-9, AD is the angular bisector of △ABC, and DE∨AB, DF∨AC, EF and AD intersect at point O. Is the angular bisector of △DEF DO? If yes, please give proof; If not, please explain why. The first triangle is 4 1. If one of the outer angles of a triangle is an acute angle, the triangle is _ _ _ _ _ _ _. 2. In △ABC, if ∠C-∠B=∠A, the smallest angle among the external angles of △ ABC is. X = _ _ _ _ _ _。 (1) (2) (3) 4. As shown in Figure 2, in △ABC, point D is on the extension line of BC, and point F is a point on the side of AB. If you extend CA to E and connect EF, then ∠ 1, ∠2, then ∠3 has a size relationship of _ _ _ _ _ _ _. 5. As shown in Figure 3, in △AB=AC, AE is the angular bisector, ∠ B = 52, ∠ C = 78. Find the degree of ∠AEB. 7. As shown in the figure, in △ ∠B and ∠D should be 30 and 20 respectively, and Uncle Li measured ∠ BCD = 142, so it is concluded that this part is unqualified. Can you tell the truth? 9.( 1) As shown in Figure 7-2-2( 1), find the degree of ∠A+∠B+∠C+∠D+∠E+∠F; (2) As shown in Figure 7-2-2-7(2), find the degree of ∠ A+∠ B+∠ C+∠ D+∠ E+∠ F. 。

1 1. As shown in the figure, BD and CD are the bisectors of the two outer corners of △ABC ∠CBE and ∠ BCF, respectively. Try to explore the quantitative relationship between ∠BDC and ∠ A. 13. An outer angle of a triangle is an acute angle. Then the shape of this triangle is () A. Acute triangle B. Oblique triangle C. Right triangle D. Uncertain 1+2x 04. The three sides of a triangle are 5, 1+2x, 8 respectively. The value range of x is _ _ _ _ _ _ _.15. As shown in the figure, BD is equally divided into ∠ABC, DA⊥AB, ∠ 1 = 60, ∠ BDC = 80, and the number of times to find ∠ C. The grade test of polygons in the first level of mathematics is 1 the bisector of triangles is () A. Straight line B. 2. As shown in the figure, the two corners of the covered triangle can't be () A. An acute angle and an obtuse angle B. Two acute angles C. An acute angle. A right angle D. Two obtuse angles 3. If one internal angle of a triangle is equal to the difference between the other two internal angles, the triangle is () A. Acute triangle B. Oblique triangle C. Right triangle D. Arbitrary triangle 4. There are two sticks with lengths of 4cm and 6cm respectively. Please find another small stick and make a triangle with these three sticks. Then the range of the length x of the third stick is x & lt6b4 < X & lt6 C. 2 & ltX & lt 10D . 6 & lt； X< 105. As shown in the figure, the degrees of the five corners of the five-pointed star on the national flag are the same, and the degree of each corner is () A.B.C.D.6. If two triangles with a common side are called a pair of * * * side triangles, there are () A.2 to B.3 to C.4 to D.6 to 7 in the * * * side triangle with BC as the common side. The three internal angles of an acute triangle are ∠A, ∠B and ∠ C. If, then, of the three angles, () A. There is no acute angle B. There are 1 acute angles C. There are two acute angles D. There are three acute angles BCD A8 ... As shown in the figure, the shape of an experimental field is a triangle (. A. Turn around 90 b. Turn around180 c. Turn around 270 d. Turn around 360 9. When the master installs the wooden door frame, in order to prevent deformation, as shown in the figure, two diagonal battens are often nailed. The principle of doing this is based on the nature of triangles. 10. As shown in the figure, the bisector extends to and intersects at this point. Xiao Min, who loves thinking, found the following rules when writing his homework: (1) If, then; (2) If yes, then; (3) If, then; According to the above law, if _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _, this triangle is .3. If all three sides of a triangle are long, then the circumference of the triangle is. 4. As shown in the figure, the paper △ABC is folded along the DE, and the point A falls on the point A'. Given that ∠ 1+∠ 2 = 100, then the size of ∠ a.

5. As shown in the figure, in △ABC, ∠ B = 32, ∠ C = 55, AD⊥BC in D and AE ∠BAC in E, find the degree of ∠EAD. 6. A yellow croaker weighs 2.854 kilograms and has two significant figures. () 7、 _____________。 8. As shown in the figure, ab ∥ CD, ∞= 45, ∠ D = ∠D=∠C, ∠ B = _ _ _ _ _ _ Washington D.C.

Ab91233 ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● The above is the word "T" made by chess pieces. How many pieces does it take to put 1 in the first "t"? What about the second one? According to this rule, how many pieces does the "t" in 10 need? 3 what about the n th one?